Possessed! The Solaris font daemon

Crusty old buffer

Common Topics

A buffer overflow risk exists in the font service which ships with Solaris. There is a workaround, but no comprehensive fix just yet.

Security clearing house CERT warns in an advisory that Solaris X Window Font Service (XFS) daemon (fs.auto) contains a remotely exploitable buffer overflow vulnerability which could allow an attacker to execute arbitrary code or cause a denial of service.

The Solaris X Window Font Service (XFS) serves font files to clients. It ships with Solaris and is included as a component in a limited number of other operating systems.

The issue effects Solaris on both SPARC and Intel platforms. NetBSD ships the xfs from XFree86, though its not turned on by default. HP is investigating the issue.

An advisory by Sun says it is working on a patch (it actually says "a final solution is pending completion" but let's leave that unfortunate turn of phrase to one side). Until patches can be applied, users are asked to consider disabling the XFS daemon (fs.auto) as a workaround. Blocking access to port 7100/TCP on firewalls is also something to consider. This will guard against possible external, but not internal, exploitation on the flaw.

The vulnerability was unearthed by security tools vendor which had planned to release its advisory in co-ordination with Sun's patch on Monday, November 25.

This hasn't happened. So has ISS jumped the gunas it allegedly did with a patch for an Apache flaw earlier this year?

That, and the release of an advisory on a BIND patch ahead of widespread availability of a fix last month, has sparked some criticism of ISS by sections of the security community, and deserves closer examination. With the Sun fix we're informed by independent researchers that the release of the advisory before the patch was down to a lack of communication between Sun and ISS, rather than self-promotion by ISS.

We've put in a request to speak to ISS' senior techies on the issues, and will bring you more on this anon. ®